Screw driver bit with double blades

ABSTRACT

A screw suspension driver with substitutable double bits which are inserted into the tip portion of the screw driver shaft. The double bits have end edges which are recessed to form stepped portions and individual of the bits at its center portion being provided with a projection adapted to be inserted into the guide hole in the screw head.

United States Patent Totsu 1 Aug. 21, 1973 [54] SCREW DRIVER BIT WITH DOUBLE 1,797,390 3/1931 Wood 145/50 A BLADES [76] Inventor: Katsuyuki Totsu, No. 4-7, 3-chome, FOREIGN PATENTS R APPLICATIONS Oshiage, Sumida-ku, Tokyo, Japan 733,857 7/1955 Great Britain 145/51 [22] Filed: July 9, 1971 [21] Appl. NO; 161,057 Primary Examiner.1ames L. Jones, Jr.

Assistant Examiner-Mark S. Bicks Related U.S. Application Data mtomey EmeSt Greenside [63] Continuation-impart of Ser. No. 737,871, June 18,

1968, Pat. No. 3,612,554.

[] Foreign Application Priority Data [57] ABSTRACT July 13, 1970 Japan /60874 A screw suspension driver with substitutable double [52] U.S. C1 145/50 E bits whi h are inserted into the tip portion of the screw [51 Int. Cl B25b 15/02 driver shaft. The double bits have end edges which are F 191d 01 seal'dl 0 50 B, recessed to form stepped portions and individual of the /50 D, 50 DA, 50 E, 50 F, 51; 279/93, 102 bits at its center portion being provided with a projection adapted to be inserted into the guide hole in the [56] References Cited screw head.

UNITED STATES PATENTS 11/1951 Eslick 145/50 E 5 Claims, 16 Drawing Figures PATENIEHJAUGZJI ma 3.753.454

sum 1 or 3 INVENTOR KATSUYUKI TOTSU PAIENIEI] A0821 I973 SHEET 2 BF 3 INVENTOR KATSUYUKI TOTSU PATENTEDAUBZI ma 3751454 SHEEI 3 BF 3 INVENTOR KATSUYUKI TOTSU SCREW DRIVER BIT WITH DOUBLE BLADES BACKGROUND OF THE INVENTION The present invention is a continuation-in-part of my US. application Ser. No. 737,871 filed June 18th, 1968 now US. Pat. No. 3,612,554 and relates, as did my earlier application, to a screw driver with screw suspension bit.

This invention relates more particularly to a a screw suspension driver having double hits at the tip of the driver shaft for tangibly holding the screw to ensure a convenient and rapid screwing operation.

I-Ieretofore, several types of the screw driver have been proposed for the common purpose of holding the screw at the tip of the driver shaft.

Conventional screw drivers of the above type, because of their relatively complicated structure require manifold steps for their manufacture with consequent difficulty in their mass production at the reduced cost. Additionally, with the known structure a smooth and convenient screwing operation was difficult and if the driver bit was damaged could not readily be replaced by a replacement for further use.

To improve the above disadvantages and inconveniencies, a screw driver is now provided for ensuring a dependable suspension of the screw in which two sheets of a of substantially the same shape and dimension are superimposed in back to back relation with a certain clearance between the two edge portions and inserted into the tip of the driver shaft to form therewith a dismantable driver bit, individual of the bit members being provided with a center pilot projection adapted to be guided into a center hole of a screw head having greater width and depth than that of a screw slot in the head, the terminal edge of each bit having somewhat a stepped portion for facilitating the insertion of the driver bit into the screw slot.

SUMMARY OF THE INVENTION It is, therefore, a general object of the present invention to provide a new screw driver which ensures a tangible suspension of the screw at the tip of the driver shaft by a simple action for the smooth and convenient screwing operation.

A principal object of the present invention is to provide a screw suspension driver which comprises a gripping portion, a driver shaft and a driver bit in which said driver bit is comprised of two sheets of the curved plate of substantially the same shape and dimension and superimposed in the back to back relation with a predetermined clearance between the two edge portions and inserted into the tip of the driver shaft to form a dismantable screwdriver, individual plates in their edge portion being provided with a center pilot projection and an edge portion laterally of the projection, which edge portion is recessed to form a stepped portion.

Another object of the present invention is to provide a screw suspension driver which comprises two sheets of the curved plate of substantially the same shape and dimension and superimposed in the back to back relation with a predetermined clearance between the two edge portions and inserted into the tip of the driver shaft to form a dismantable screwdriver, individual elastic plate in the edge portion being provided with a pilot projection adapted to be guided into a center hole of a screw head the hoie being of greater width and depth than that of a screw slot on the head.

A further object of the present invention is to provide a screw suspension driver which comprises two sheets of the elastic plate of the same shape and dimension and superimposed in the back to back relation with a predetermined clearance between the two edge portions and inserted into the tip of the driver shaft to form a dismantable screwdriver, individual plate at its half side edge being somewhat recessed to form a stepped portion for facilitating a smooth insertion of the bit into the screw slot.

Yet a further object of the present invention is to provide a screw suspension driver bit which is comprised of two individual bit pieces of substantially rectangular form with tail insertions at one side and center projection with recessed portions at the opposite side said two bit pieces being superimposed together in the back to back relation with a predetermined clearance between the two edge portions.

Still a further object of the present invention is to provide a convenient combination of the screw driver according to the present invention with a screw of the type having the screw head which is provided at its center portion with a substantially cylindrical and vertical hole bisecting the screw slot at a greater width and depth than that of the screw slot.

Another object and advantageous of the present invention will be more fully described hereinafter with reference to the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a perspective view of the screw driver according to the present invention;

FIG. 2 is a fragmentarily enlarged front elevation of a single bit piece forming a part of the double driver bit in accordance with the present invention;

FIG. 3 is a lateral view of FIG. 2;

FIG. 4 is a fragmentarily enlarged front elevation of a single bit piece of the second embodiment in accordance with the present invention;

FIG. 5 is a fragmentarily enlarged front elevation of a single bit piece of the third embodiment in accordance with the present invention;

FIG. 6 is a fragmentarily enlarged sectional view of the tip of the driver shaft of FIG. 1;

FIG. 7 is a bottom view of FIG. 6;

FIG. 8 is a side view in section of the bit attached to the tip of the driver shaft;

FIG. 9 is a front elevation of FIG. 8;

FIG. 10 is a perspective view of the screw for use with the screw driver in accordance with the present invention;

FIG. 11 is a fragmentarily enlarged side view in section of the driver bit in accordance with the present invention illustrative of the situation on contact with the screw head;

FIG. 12 is a sectional elevation taken along the line XII-XII of FIG. 11;

FIG. 13 is a fragmentarily enlarged side view in partially sectioned of the driver bit in conjunction with the screw according to the present invention;

FIG. 14 is a pictorial view illustrating a mode of the insertion of the bit of FIG. 5;

FIG. 15 is a side view of the flat head screw in engagement with the driver bit in accordance with the embodiment of FIG. 5; and

FIG. 16 is a fragmentarily enlarged front elevation in partially sectioned of the driver bit attached with a sleeve adapter in stabilizing the flat head screw.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in more detail to the drawing, wherein like parts are indicated by like reference numerals and initially to FIG. 1, there is illustrated therein in a perspective view a screw driver which comprises the grip portion 10, the driver shaft 12 and the driver bit 14 which comprises two sheets of flat plates which are superimposed one another to form an elastic bit.

As best shown in FIGS. 2 and 3, individual plate 16 comprises a main body 18 of substantially rectangular form and is provided with a projection 20 extending downwardly from the middle portion of the lower edge 22 of said main body 18. The projection 20 has a width greater than that of the screw slot.

A half side of the lower edge 22 of the plate 16 extending from the route of the projection 20 is preferably somewhat recessed to form a stepped portion 24 for facilitating a smooth insertion of the bit into the screw slot on the screw holding operation as hereinafter fully described. From the upper end of the main body 18 is extended a slender tail 28 with a certain degree of curvature as shown in FIG. 3.

An embodiment of the bit piece shown in FIG. 4 has only a projection 20 and no stepped portion recessed. On the other hand, an embodiment of the bit piece shown in FIG. is formed of a stepped portion 24 only but free from any projection. The functional advantages and operational characteristics of those embodiments will be described hereinafter.

The plates 16 thus formed are superimposed as a pair in the back to back relation with a certain clearance between two edge portions and inserted into the tip of the driver shaft. As best shown in FIGS. 6 and 7, the shaft at its end portion is provided with a groove 30 for embracing the bit and with a substantially cylindrical hole 32 of larger diameter than the width of said groove 30. The bit holding groove 30 has somewhat wider width than the sum thickness of the superimposed plates 16, 16 and a depth sufficient to accomodate an upper half of the main body 18.

When the superimposed plates l6, 16 at their tails 28, 28 are inserted into the tail insertion hole'32 of the shaft 12 with the insertion of the main body 18, 18 substantially in their halves into the bit holding groove 30, the tails 28, 28 are stressed for the inner wall of the holding groove 30 under the elastic function of the tails whereby the plates l6, 16 forming an elastic bit are rigidly held at the tip of the shaft 12 as best shown in FIG. 8.

In this case, the width of the bit embracing slot 30 is designed in such a way that the two plates l6, l6 tending to open a part from one another by elasticity are tightly closed therein while permitting to leave a little clearance therebetween, and the clearance formed in the opened state of the superimposed plates l6, 16 at their lower edge 22, 22 including the thickness of the bit, is of somewhat greater width than the width of the screw slot formed in the screw head.

The plates l6, 16 must be superimposed in such manner that the stepped portion 24 formed at the edge portion 22 of the plate 16 is positioned in alignment with the stepped portion 24 formed at the half edge portion of the other plate 16 but displaced therefrom in a plane parallel to that containing edge portion 24. That is, in an ordinary right directional screw driver, it is always required to position the stepped portion 24 at the left side as best shown in FIG. 9.

FIG. 10 shows a screw which is most effectively used with the screw driver of the present invention.

In accordance with this screw 34, the screw head 36 is provided with a straight slot 38 and a guide hole 40 provided at the middle portion of the screw head 36 to bisect the screw slot 38 in such a fashion that it has a greater diameter and depth than those of the screw slot.

A typical operation of the screw driver in accordance with the present invention will be more fully described hereinafter.

At first, the edge portion 22 of the driver bit is placed on the surface of the screw head 36 following an insertion of the projection 20 into the guide hole 40 provided in the screw head 36 so that the driver bit even in any direction may be inserted into the screw slot 38 in accordance with the following turning action of the screw driver.

That is, the screw driver is then somewhat turned for the screwing direction of the screw 34 as usually right direction and then the edge portions 22, 22 of the double bit located in the diagonal positions around the projection 20 falls into the screw slot 38 across the slot in somewhat tilted fashion leaving the stepped edges 24, 24 out of the screw slot as best shown in FIGS. 11 and The screw driver is further turned to the screwing direction of the screw so that the clearance between the two bit pieces at their edges may be constricted under the pressure and finally the stepped edge portions 24, 24 are brought to fall into the slot thereby to accomplish an insertion of the double bit into the screw slot 38 as best shown in FIG. 13. In this connection, a clearance originally given between the two bits is desired to have a degree sufficient to assure a smooth insertional operation of the double bits into the screw slot and usually at a proportion of one fourth total thickness of the double bits.

In order to ensure a smooth insertional operation of the double bit into the slot, it will be appreciated that the edge portions of the double bits are inevitably placed on the screw head along the line intersecting with the screw slot at its center portion and maintained on the same right position throughout the insertional operation. This is accomplished by first coupling the projections 20 provided at the center of bit edge with the guide hole 40 of the screw 34 which has a wider diameter than the width of the screw slot 38 and then inserting the non-recessed edges in screw slot 38.

The double bits thus inserted into the screw slot are closed together as if they form a single bit while stressing both side walls of the screw slot over their whole area under the elastic pressure so that an engagement of the screw with the driver bit is not released only by the weight of the screw and even by a light impact.

In the situation of the above engagement, since the projections 20, 20 are fitted into the bottom of the guide hole 40 having greater depth than the screw slot, any likehood of the lateral slipping of the double bits on the bottom of the screw slot may be tangibly prevented.

In accordance with the second embodiment of the present invention having no recessed edge as provided in the first embodiment, the insertion of the double bits are effectuated in such a way that the projections 20, of the double bits are first inserted into the guide hole of the screw head and simultaneously the edges of the double bits are placed in some tilting relation with the surface of the screw head by the habitual motion of the operator and once any corner of the edges of the double bits falls into the screw slot, the insertional action as illustrated in connection with the first embodiment may be attained.

The double bits of the third embodiment is applicable to the screw of either flat or round head with a usual slot but without a guide hole as best shown in FIGS. 14 and 15. In this case, since the guiding function obtain able by the center pilot projection as provided in the first and second embodiments can not be expected, another suitable stabilizing means may preferably used with the driver bit. In this invention, a sleeve adapter 42 is mounted around the bit portion so as to loosely cover the screw head as can be seen in FIG. 16. It should be noted that this sleeve adapter may also be advantageously used for the screw suspension driver of the first and second embodiments to enhance the stable screw holding operation.

While, certain preferred embodiments of the invention have been illustrated by way of example in the drawings and particularly described, it will be understood that modifications may be made in the constructions and that the invention is no way limited to the embodiments shown. For example, the thickness of either individual bit piece of double bit may be selectively regulated to increase toughness of the bit.

I claim:

1. A screw suspension driver including a gripping portion, a driver shaft extending at one of its ends from the gripping portion, and a screw suspension bit extending from the other end portion of the driver shaft, said bit comprising two sheets of elastic bit members of substantially the same shape and having a portion inserted into the tip end of the driver shaft with the members in back-to-back relation, and with a predetermined lateral separation between the outwardly projecting end edge portions of said elastic members, each said end edge portions of each bit member having terminal edges lying in vertically spaced-apart planes and adapted for insertion in a screw slot.

2. A screw suspension driver comprising a gripping portion, a shaft portion extending at one end thereof from said gripping portion, and a screw suspension bit extending from the opposite end of said shaft portion, said screw suspension bit comprising a pair of likeshaped flexible members supported by said shaft portion in back-to-back relation and with the tip end portion of said flexible members resiliently urged in spaced apart relation a predetermined distance, each flexible member terminating in first and second edges, the first of which is recessed with respect to the second, each of said second edges of said pair of members being adapted upon predetermined orientation to enter a screw slot of width less than said predetermined distance and bearing, upon rotation thereof, against walls of said slot to reduce the distance between the tip end portions of the bit whereby to permit entry of said first edges of said pair of members in said slot.

3. A screwdriver according to claim 1, wherein each bit member has a substantially rectangular form and includes a tail portion within the driver shaft extending from one side of the rectangular form and a center projection at an opposite side of the rectangular form, said terminal edges extending in opposite lateral directions from said center projection.

4. A screwdriver according to claim 3, wherein said predetermined lateral separation between the facing inner surfaces of the outwardly projecting end edge portions of said elastic members is one fourth the distance between the outwardly facing surfaces of the bit members.

5. A screwdriver according to claim 1 wherein the driver shaft at its tip end portion is provided with a sleeve extending beyond said bit.

I 1 i i 

1. A screw suspension driver including a gripping portion, a driver shaft extending at one of its ends from the gripping portion, and a screw suspension bit extending from the other end portion of the driVer shaft, said bit comprising two sheets of elastic bit members of substantially the same shape and having a portion inserted into the tip end of the driver shaft with the members in back-to-back relation, and with a predetermined lateral separation between the outwardly projecting end edge portions of said elastic members, each said end edge portions of each bit member having terminal edges lying in vertically spacedapart planes and adapted for insertion in a screw slot.
 2. A screw suspension driver comprising a gripping portion, a shaft portion extending at one end thereof from said gripping portion, and a screw suspension bit extending from the opposite end of said shaft portion, said screw suspension bit comprising a pair of like-shaped flexible members supported by said shaft portion in back-to-back relation and with the tip end portion of said flexible members resiliently urged in spaced apart relation a predetermined distance, each flexible member terminating in first and second edges, the first of which is recessed with respect to the second, each of said second edges of said pair of members being adapted upon predetermined orientation to enter a screw slot of width less than said predetermined distance and bearing, upon rotation thereof, against walls of said slot to reduce the distance between the tip end portions of the bit whereby to permit entry of said first edges of said pair of members in said slot.
 3. A screwdriver according to claim 1, wherein each bit member has a substantially rectangular form and includes a tail portion within the driver shaft extending from one side of the rectangular form and a center projection at an opposite side of the rectangular form, said terminal edges extending in opposite lateral directions from said center projection.
 4. A screwdriver according to claim 3, wherein said predetermined lateral separation between the facing inner surfaces of the outwardly projecting end edge portions of said elastic members is one fourth the distance between the outwardly facing surfaces of the bit members.
 5. A screwdriver according to claim 1 wherein the driver shaft at its tip end portion is provided with a sleeve extending beyond said bit. 